calculator/complex locus

[Flaming_Arrow]

But funny thing is if you solve on the TI-89 you get an ellipse equation?  :uglystupid2:

how do u solve that on the calc?




Moderator Action: Topic split from http://vcenotes.com/forum/index.php/topic,18005.0.html , off-topic discussion
-Mao

[kurrymuncher]

But funny thing is if you solve on the TI-89 you get an ellipse equation?  :uglystupid2:

how do u solve that on the calc?

Just sub in z=x + yi  and the calc will expand it into cartesian form.

[TrueTears]

Right, now that it is a typo, how come the original question still is an ellipse (according to calc) yet when I do it by hand I get a straight line?

kamil had no idea, anyone else?

[Flaming_Arrow]

But funny thing is if you solve on the TI-89 you get an ellipse equation?  :uglystupid2:

how do u solve that on the calc?

Just sub in z=x + yi  and the calc will expand it into cartesian form.

ye i know how to to do that, i thought it would solve the whole equation and give it in terms of x and y

[TrueTears]

But funny thing is if you solve on the TI-89 you get an ellipse equation?  :uglystupid2:

how do u solve that on the calc?

Just sub in z=x + yi  and the calc will expand it into cartesian form.

ye i know how to to do that, i thought it would solve the whole equation and give it in terms of x and y

Nah you can rearrange yourself though.

[/0]

Right, now that it is a typo, how come the original question still is an ellipse (according to calc) yet when I do it by hand I get a straight line?

kamil had no idea, anyone else?

What did you do?
Did you do this?



That would give you a complex number on the RHS... did you then set y = 0??

[TrueTears]

Right, now that it is a typo, how come the original question still is an ellipse (according to calc) yet when I do it by hand I get a straight line?

kamil had no idea, anyone else?

What did you do?
Did you do this?



That would give you a complex number on the RHS... did you then set y = 0??

Nah I just subbed in z = x+yi , as in I typed x+yi instead of z on the calc.

[/0]

But that still leaves you with
, what did you do then?

[TrueTears]

But that still leaves you with
, what did you do then?

Oh nah on the calc I modded both sides again

ie, ||z-2i|| = |4-z|

[kamil9876]

modding both sides is not valid. It's even worse than squaring both sides. It gives you a completely different locus as /0 showed, the original one is a single point, but the "modded" one is not a single point. Turning our attention to the "modded" one as a seperate problem itself, |z-2i|=|4-z| is a straight line. I'm suspecting that putting in ||z-2i||=|4-z| instead screwed things over and made the calc do something unintelligent.

But please take the moral of the story - for the 999th time - as "do not mod both sides, it changes locus since it is irrevirsible", as shown by /0's post earlier.

[TrueTears]

modding both sides is not valid. It's even worse than squaring both sides. It gives you a completely different locus as /0 showed, the original one is a single point, but the "modded" one is not a single point. Turning our attention to the "modded" one as a seperate problem itself, |z-2i|=|4-z| is a straight line. I'm suspecting that putting in ||z-2i||=|4-z| instead screwed things over and made the calc do something unintelligent.

But please take the moral of the story - for the 999th time - as "do not mod both sides, it changes locus since it is irrevirsible", as shown by /0's post earlier.

Nah I'm referring to a completely different thing, not the the question the OP posted.

I'm saying how come if you have ||z-2i||=|4-z| and solve by hand you get a straight line, but you solve on TI-89 you get an ellipse as /0 confirmed earlier.

But please take the moral of the story - for the 999th time - as "read what I said on msn properly"

[/0]

I never said it was an ellipse...

Inputting:

[kamil9876]

THe point I am making is still valid, and turns out I'm correct:

TrueTears] says (1:45 AM):
 yeah
 it gives line
 if u put in
 | |

[TrueTears]

But funny thing is if you solve on the TI-89 you get an ellipse equation?  :uglystupid2:

Hmm.... yeah that's weird... but then you could also say like

because

You just said "hmmm ... yeah..." to my ellipse equation.

THe point I am making is still valid, and turns out I'm correct:

TrueTears] says (1:45 AM):
 yeah
 it gives line
 if u put in
 | |

What does that show? I never asked about putting in | | and | | on both sides, I asked about what if you put || || on LHS and | | on RHS. What are you on about? You didn't really solve anything, I asked the reason for why does the calc spit out an ellipse equation when it's meant to be a line. Did I ever say it wasn't a line?

[/0]

Right, now that it is a typo, how come the original question still is an ellipse (according to calc) yet when I do it by hand I get a straight line?

kamil had no idea, anyone else?

You modded both sides of the original equation, which was